Support Python 3.12

[agriyakhetarpal]

Description

Related to #3390. Adds support for Python 3.12 across the repository

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (4ad2853) 99.59% compared to head (61cc1c8) 99.59%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3531   +/-   ##
========================================
  Coverage    99.59%   99.59%           
========================================
  Files          258      258           
  Lines        20755    20755           
========================================
  Hits         20670    20670           
  Misses          85       85           

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[Saransh-cpp]

Thanks @agriyakhetarpal! I think it would be better to remove the install_PyBaMM function because I think the function is redundant and is complicating simple things.

[agriyakhetarpal]

I have now removed the install_PyBaMM() function and used some extra conditions instead. Doing this will bring many conflicts with some of my other PRs, but I can rebase any of them depending on whichever ones will get merged first. I have also added many # TODO: comments as a note to myself since I shall be working with these files again very soon.

[Saransh-cpp]

@agriyakhetarpal could you rebase this?

[agriyakhetarpal]

@agriyakhetarpal could you rebase this?

I just noticed this comment—I think there will be many merge conflicts here and there and they will be repeated a lot as the latest changes are added upstream—perhaps I can rebase this branch here on top of the changes in #3550, or just wait for #3550 to be reviewed and get merged first. I haven't worked on the installation guide yet to adjust for both of the PRs since they will require changes to it, but I shall do that as soon as possible next week.

[brosaplanella]

Looks good, thanks!

[arjxn-py]

Thanks @agriyakhetarpal, looks good.

[Saransh-cpp]

Thanks, @agriyakhetarpal! This should also remove all the instances of distutils from the codebase. We are importing distutils in setup.py at the moment.

[Saransh-cpp]

Thanks, @agriyakhetarpal! Looks good!